why does fur after combing act unpredictably?
When setting up particle hair we normally configure a small number of hairs, then use children hairs that get created around each existing hair to fill out for the render.

The children hair settings have options that make them curl up or clump together around the parent hair. I think the bending and clumping you see is the children hairs being deformed by these settings after they are shown. Most likely this is because in particle edit mode you aren't showing any children, so when they show up in object mode they look much different. While in particle edit mode you can turn on the option to display children hairs. This is in the toolbar T under Options.



For performance we normally only display a portion of the children hairs while grooming the hair, and use more hairs for a better final image. These options are found in the Children panel of the particle settings. Display is how many children we see in the 3dview, while Render is how many are used at final render stage. If you set these the same while grooming the hair you will see less change at render time. Once finished grooming you may want to turn Display back down to keep the 3dview responding.